Motor



- Dec. 26, r1939. w. H. wlNEMAN MOTOR Filed Sept. 17. 1935 2 Sheets-Sheet 1 Ku@ 9 J; N/ Y 440,0 au

mm W m M M w Dec. 26, 1939. w. H: wlNEMAN MOTOR Filed sept. 17, 1955 f m11 M .wwf W w a A 3 j f Z ,F

Patented Dec. 26, 1939 Wade H. Wineman, Michigan City, Ind., assignor to Sullivan Machinery Company, a corporation of Massachusetts Application September 17,1935, Serial No. 40,949 31 Claims. (Cl.' 121- `1`50) My' invention relates to expansible chamber motors, and more particularly to expansible chamber motors of the type especially adapted for pumping and similar uses.

iields where there is available a considerable quantity of oil but insucient pressure in the strata to' cause the oil to rise to the surface, steam or pneumatically operated, single-acting pumping motors have been used to great advantage for lil actuating through a suitable pump rod line pumps arranged down in the oil wells. Such pumping motors are commonly, though not always, arranged in groups adjacent a central source of operating pressure fluid supply, and individual l pumps are notattended continuously by pump runners. As a result it is imperative to make the pumping motors as nearly completely automatic and self-protective as possible.

It is an object of the present invention to pro- Vide an improved expansible chamber motor. It is another object of my invention to provide an improved expansible chamber motor having improved distributing valve means. It is a further object of the present invention to providev an improved expansible chamber motor having improved means for preventing breakage in the event that the motor loses its load suddenly. It is still another object of the present invention to provide an improved automatic vent check valve up in association with an expansible chamber motor `for the purpose of protecting the same against breakage in the event of over-stroking, while at the same time interfering practically not at all' with the normal operation of the motor. Other objects and advantages of the invention will hereinafter more fully appear.

In the accompanying drawings, in which for purposes of illustration one embodiment which the invention may assume in practice has been 4U shown,

Fig. 1 is a side elevation of a pumping motor cylinder in which my invention is embodied in an illustrative iorm, v

Fig. 2 is a view partially in side elevation and pumping motor of Fig. l,

Fig. 3 is a horizontal section on an enlarged scale on the plane corresponding to line 3-3 of Fig. 2, showing the distributing valve in exhaust position,

Fig. 4 is a similar view showing thedistributing valve mechanism in admission position,

Fig. 5 is an enlarged fragmentary sectional view on the same planes as Figs. 3 and 4, showing In certain oill is shown. The uid supply may be at a pressure partially in central vertical section through the details. of the distributing valve control mechanism, Fig. 6 is` an enlarged central Vertical section through the vent check valve mechanism, Fig. 7 isy afragmentary sectionthrough the 5 cylinder wall on the plane ofthe section line l-"I of Fig. 2.

Referring first to Fig. 1, it will be observed that suitable supporting means 2 carries a motor de.

vice 3 whichv comprises an upper head member t, 10

a lower head member 5, anda cylinder member 6. The cylinder 6 has a bore l in which a piston 3' is reciprocable, and a piston rod 9 connected to the piston 8 is adapted to be connected to'a pump rod line. The piston 8 is a single-acting 15 piston and is adapted to be raised by pressure fluid admitted beneath the same and to be moved downwardly upon a reduction in the pressure beneath the piston by the weight of the` pump rod line, its own weight, etc. The lower cylinder 20 head 5, which is connected to the upper head 4 by a series of tie'rod devices IB, is provided with a Valve chest and supply and discharge connection generally designated I2. This comprises a v motive fluid supply space I3 to which fluid is 25 supplied through a supply connection I4, of which but a fragment 1s shown. It also comprises an exhaust connection I5 which is connected tov an exhaust connection I6, of which but a fragment 0 of 200 or 300 pounds per square inch, for example, and the exhaustconnection is maintained by suitable means, not shown, under a back pressure of perhaps '75 to 100 pounds, the` pressure used depending Y upon the operating conditions.r A 35 connection il leads to the bottom of the cylinder boreI 1f; The supply space and the cylinder port I'l are separated by septumy I9, and the exhaust spacev I5 and cylinder port Il are separated by sep-tum 2i). A suitable valve-chamber-forming element 2l is mounted in a series of vbores of progresively decreasing sizes 22, 23, 24, 25, and is Aprovided with shoulders as at 26 adapted to seat upon supporting surfaces 2l, and is secured in position in any suitable manner. A head 28 held in position by screws 29 is arranged opposite the i valve chest member 2 I and has a reduced portion 30 which extends into the bore 3l of vthe valve chest member. It will be noted that the valve chest member is not a close nt at 32 at its exhaust 50 end for thel member I2, and a connection 33 conlnects'the exhaust space l5 with the exhaust end of the bore 3l. .The bore 3| is connected by ports 34 with the exhaust space, by ports 35 with the cylinder port, and by ports 36 with the supply 55 space I3. Within the bore 3! a valve element di! is reciprocably mounted. This includes a suitably ringed head 4i connected by a reduced portion d2 with another ringed portion 43, the portions il and 43 tting the bore 3l. Beyond the portion 43 the member 46 has an enlarged head fifi which iits in an enlarged bore 45 alined with thebore I may be suitably vented, if desired.

It will be noted that between the portions 4| and 49 there is provided a distributing groove 41 which, in the position of the parts shown in Fig. 4, connects the ports 95 and 36 and enables the admission of uid beneath the motor cylinder.

In the position of the parts shown in Fig. 3 the space 41 connects the cylinder port l1 with the exhaust.

Since the exhaust space l5 is maintained under a substantial back pressure as above noted, it will be evident that there will always be ay substantial pressure acting upon the exhaust end of the valve piston portion 4l, and, accordingly, in the absence of counter-pressures, the valve member f-ll will occupy the position shown in Fig. 4. Suitable means is provided for periodically moving the valve member 40 out of that position into the position shown in Fig. 3, and for maintaining it in the latter position for the necessary periods. Referring to Figs. '1' and 2, it will be observed that a suitable connection 50, whose upper end may be connected at any one of a series of positions 59 to the bore of the cylinder, at its lower end is connected through a coupling 5l to a central passage 52 formed in a sleeve member 53, supported in a cover member 54 for the valve chest 2|. At its inner end the member 53 provides a conical seat 55 with which a conical tip 56 upon a spring-pressed plunger 51 mounted within a retaining plug 58 is adapted to engage. It will be noted that the spring 59 which acts upon the lower end` of the member 51 normally. maintains the latter projected a certain distance beyond the end surface 60 of the valve head 44, and that when the valve member 46 is in the position shown in Fig. 4 portion 56 seats in and eects a seal with the conical recess 55. Accordingly, since the spring 59 is of such strength as to prevent unseating of the valve portion 56, even by full cylinder pressure, when the valve member 46 is in its position of Fig. 4, it will be requisite for the valve member 40 to move a short distance from the position shown in Fig. 4 before the space within the cylinder bore 1 will be placed in free communication with the surface 66, through the passage 59.

It will also be noted that a suitable connection 62, which may be connected as desired through different ones of a series of openings 62 with the cylinder bore 'i near the upper end of the latter, leads to a connecting plug 63 which holds a valvereceiving chamber member 64 in position in the head 54. Within the member 64 is a spring 65 which presses a tapered valve element 66 having a projecting stem 61 normally to its seat 68. Passages 69, sealed when the valve 66 is on its seat 68, aiord, when the valve 66 is unseated, a

connection between the passage 62 and the main valve surface 66, such connection being via a passage 16 in the plug 63, the bore through the member 64, the passages 69 in the valve, and around the stem 61 of the latter, there being clearance at that point.

The spring 65 is of such strength as normally to maintain the stem 61 projected into the space in which the distributing valve head 44 moves The space 66 at its end nearer the bore 3i and concurrently maintain the valve 66 on its seat. When the valve 40 is moved to the position of Fig. 4 its surface 60 will engage the stem 61 and move the valve 66 to open position and hold it there with the surface 6l) in communication with the passage 62, and so with the cylinder bore 'l at the point 62 to which the connection 62 is connected. It will be understood, of course, that all the inactive connection points 56 and 62 will be sealed by suitable plugs.

The cylinder member 6 is provided with a series of by-pass passages or enlargements 15. These, it will be noted, provide a series of circumferentially arranged, longitudinally extending clearances so that the piston 8 may travel substantially freelybetween the ends of these by-passes. Above the upper end of the by-passes the end of the cylinder may be largely or completely sealed, as may be desired.

To permitI downward movements of the piston without retardation due to sub-atmospheric pressure above the piston, I provide suitable means for admitting pressure fluid to one of the by-pass connections, and also provide means for permitting substantially unrestricted discharge through said same connection so long as the piston moves at a normal rate, but such means is made operative to provide a retardation to the travelof the piston whenever the piston movement in its working direction is at an excessive rate. It will be observed that one of the by-pass spaces 15 is connected through a connection 11 with a valve body 18 Whose interior is divided by a septum 19 into two chambers, respectively 86 and 6l chamber 86 communicating with the cylinder bore and chamber 8l communicating through a pipe 82 with an air cleaner 83. A port 84 in the septum 19 provides a seat 85 for a check valve 86 whose stem 6l normally rests upon an adjustment screw 88 which may be positioned to permit the valve 66 to be cfr" of its seat normally at all times by any predetermined desired amount. A small port 69 connects the chambers 86 and 8|. Valve 66 will not be adjusted to a position in which an abnormal rush of fluid through the connection 11 may not lift it to its seat.

The mode of operation of the entire apparatus may now be briey described. Starting with the piston in the position shown in Fig. 2 and with the valve 49 in the position shown in Fig. 4, it will be noted that motive iluid supplied through the connection I4, chamber i3, ports 36, valve groove 41, and ports 35 and cylinder port l1, will pass beneath the piston 8 and move the latter upwardly. As the piston moves up it will rst place in communication with the cylinder bore 1 the upper end of the connection 59, but no uid under cylinder pressure will pass through the connection 5U to act upon the distributing valve surface 66, because the valve element 56 Will, in the position oi the parts in Fig. 4, rest upon the seat 55 and preclude such flow. The piston S will, therefore, continue its upward movement under continued supply of motive fluid until the lower end of the piston 8 passes above the active opening 62 and permits the ingress oi cylinder pressure to the connection During this normal piston travel described the air above the piston will be displaced readily through the connection 89 and through the passage 64, primarily through the latter of course. When the connection 62 has been brought into communication with the cylinder bore, cylinder pressure will pass therethrough, through the passage 10, through the port 69 in the then unseated valve 66, around the stem 61, and act upon the surface 60 and force the valve 40 sufficiently far toward the position of Fig. 3 so that the valve 56 will unseat. It .will be understood that the valve 56 should unseat before the valve '66 seats. Thereupon, although the valve S6 will promptly seat, pressure will flow from the cylinderv bore through the connection 5U, connection 5I, passage 52, and into the bore 45, and move the valve it into the position shown in Fig. 3. `Although the space below the piston will be connected to the exhaust'space when the valve is shifted, it will be noted that the pressure transmitted to the surface 60 will be higher at least until the valve is fully thrown than the exhaust pressure, andl moreover itwill be observed that the surface 60 is larger than the area of the head di' exposed to an exhaust pressure, and so the valve il@ will be maintained in the position of Fig. 3 throughout the exhaust stroke of the piston 8. As soon as the lower end of the cylinder bore 'l is connected through the passage il, ports 35, groove il and ports 3ft' to the exhaust space l5, the weight of the parts supported by the piston 8 will move the latter downwardly and force out the motive pressure beneath the piston against the back pressure. It will be appreciated that during the downward stroke of the piston 8, air will pass into the upper end of the cylinder bore through the connection 82, past the valve 8, and somewhat through the port 89 and through the connection 1l, into the cylinder bore.

When the upper end of the piston` 8 places the il and the valve chest head 54 Will occur, and,

since this venting is tol atmosphere the back pressure which acts upon the relatively large area of the head il will promptly move the valve tu to the position shown in Fig. 4 again, and when the valve di) reaches that position, valve 5B will seat and valve 66 will be unseated, and the motor will be ready to make another working stroke in the manner described. v

In the event that the pump rod'breaks, or the pump packing ruptures, it Will be understoodthat the piston 3 will be freed of its load to suchan extent that its upward movement will be at a much higher rate than its normal rate of movement. Therefore, there will be a much more rapid compression of the air above the piston and a tendency of the air to rush more rapidly through the connection l?. This will cause the valve 86 to be raised to its seat, and the only venting then possible will be through the passage 89, and there will, therefore, be an early commencement of cushioning of the upward movement of the piston 8 and after the piston travels above the by-pass passage l5 there will be entrapped above it air already at considerably above atmospheric pressure (for it will be understood that cylinder pressure which will not have had time to be reduced to exhaust line pressure can also pass the piston as the latter is traveling between the ends of the by-passes), and the piston will be brought to rest without damage.

From the foregoing description it will be appreciated that I have provided a highly efficient apparatus for a wide number of purposes, and particularly forl the performance of pumping operations in oil-fields of the character described. It will benoted ,that the parts are simple, that there is no possibility of the valve mechanism ever operating to connect the supply and exhaust connections due to incomplete operation,that breakage ofthe parts due to blowing out of the packing, or breaking of the pump line,

is very eifectually prevented, and that the whole apparatus is rugged and absolutely positive in its operation.

' While I have in this application specifically described one form which my invention .may assume in practice, it will be understood that this form of the same is shownfor purposes of illustration, and that `the invention may be modione end thereof to motor back pressure, said-backv pressure being in excess ,of` atmospheric pressure, andmeans for alternatively subjecting the other end thereof throughout nearly complete Ypiston travels in opposite directions `to cylinder pressure and to atmospheric pressure. ,y 2. In a motor, in combination, a cylinder, a pistonv reciprocable therein, means for continuously Venting one end of said cylinder, and means for controlling admission and exhaust with respect lto the opposite end of the cylinder .including a valveperforming both admission and exhaust functions and throwing means for said Valve including means for continuously subjecting one end thereof to a pressure less than working cylinder pressure but in excess of atmospheric pressure, and means for alternatively subjecting the'other end thereof throughout nearly complete piston travels in opposite directions'to cylinder pressure and to atmospheric pressure.

3. In a motor, in combination, acylinder, a piston reciprocable therein, means forcontinuously venting one end of said cylinder, and means for controlling admission and exhaust with ref' ciated therewith means for trapping the throwing pressure during the major portion of piston movement in one direction.

4. In a motor, ,inl combination, a cylinder, a

fos

piston reciprocable therein, means l for continu-` ously venting one end of said cylinder, and means for controlling admission and exhaust with respectto the opposite end of said cylinder including a valvel operative in opposite positions to 'effect the admission" and exhaust functions.v

vValve in the opposite direction by cylinder pres-v sure, said last-mentioned means having associated therewith means, including a distributingvalve-controlled check valve, for trapping the throwing pressure during the major portion of piston movement in one direction.

5. In a motor, in combination, a cylinder, a piston reciprocable therein, means for admitting and exhausting motive fluid with respect to one end ci the cylinder, and means for substantially freely venting the other end of the cylinder tov atmosphere during normalrnovements of said piston by the motive iiuid supplied thereto and for automatically cushioning abnormal movements of said piston in a Working direction including means for connecting the other end of the cylinder to atmosphere providing respectively different areas of communication with the atmosphere automatically independence upon the rate of piston movement, the larger area adequate to providey for substantially unrestricted discharge of airv during normal Working piston movements.

5. In a motor, in combination, a cylinder, a piston reciprocable therein, means for admitting and exhausting motive fluid with respect to one end of the cylinder, and means including a valve governed by fluid displaced by the piston for connecting the other end of the cylinder to atmosphere providing different areas of communication with the atmosphere automatically. in dependence uponthe rate of piston movement, the larger area such as to preclude the opposition of any substantial pressure to piston movement during normal Working strokes of the latter and said valve movable to close said larger area of communication.

7. In a motor, in combination, a cylinder, a piston reciprocable therein, means for admitting and exhausting motive fiuid with respect to one end of the cylinder, and means for substantially freely venting the other end of the cylinder to atmosphere during normal movements of said piston by the motive duid supplied thereto and for automatically cushioning abnormal movenic-nts of said piston `in a Working direction including means for connecting said other end of the cylinder to atmosphere including respectively valved and unvalved passages and providing different areas or" communication automatically in dependence upon the rate of piston movement, the larger area valve controlled and adequate to preclude material resistance of fluid pressure on the non-Working side ci the piston during normal Working strokes of the latter.

8. In a motor, in combination, a cylinder, a piston reciprocable therein, means for admitting and exhausting motive fluid with respect to one end of the cylinder, and means for connecting the other end ci the cylinder to atmosphere including respectively valved and unvalved passages and providing different areas of communication, the latter the smaller, automatically in dependence upon the rate of piston movement, said valved passage having a controlling valve normally maintained open by gravity and governed by fluid displaced by the piston and providing anA area of communication with the atmosphere Sunicient to preclude substantial resistance to piston movement or building up of substantial fluid pressure tending to close said valve during normal Working piston movements.

9. In a motor, in combination, a cylinder, a piston reciprocable therein, means for admitting and exhausting motive fluid with respect to one end of the cylinder, and means for controlling over-movement ofthe piston in a Working direction including a bypass for supplying pressure in advance of the piston and associated means for automaticallyv checking displacement of uid by said piston, upon abnormally rapidvmovement thereof, prior to the latters attainment to said bypass. Y

l0. In a motor, in combination, a cylinder, a piston therein, a distributing valve for controlling admission and exhaust of fluid relative to one end of said piston, and valve-controlling means including cylinder-connected passages having controlling valves respectively carried and actuated by said distributing valve and controlling diiferent ones of said cylinder-connected passages.

ll. In a motor, incombination, a cylinder, a piston therein, a distributing valve for controlling admission and exhaust of huid relative to one end of said piston, and valve-controlling means including plurality of cylinder-connected passages communicable with the same end of the valve and having controlling valves respectively carried and actuated by -said distributing valve and controiling different ones of said cylinderconnected passages,

3.2. In a motor, in combination, a cylinder having a bypass passage intermediate its ends and an atmospheic communication for said bypass, a piston normally reciprocable in said cylinder short of either end of said by-pass, means for effecting such normal reciprocation, and an automatic check valve controlling the degree of commimication of said bypass with the atmosphere.

13. In combination, a motor comprising a cylinder with a piston normally reciprocable therein in a predetermined path and having means for supplying Working huid to and venting it from one end of the cylinder', and means for substantially freely venting the other end of the cylinder to atmosphere during norma'movements of said piston by the motive rluid supplied to the latter and for checking piston movement should its normal path be exceeded by increasing the uid resistance to piston movement, including means for providing a substantially free discharge of iuid from the non-working end of the cylinder during normal piston movement and for automatically, upon abnormal movements of the piston, reducing the freedom of displacement of fluid in advance ci said piston while maintaining a predetermined limited. freedom of displacement of fluid.

le. In combination, a motor comprising a cylinder with a. piston normally reciprocable therein in a 'predetermined path, means for autornaticaily checking piston movement should said path be exceeded including means for increasing the fluid resistance to piston movement including both means for reducing the freedom oi' displacement of duid in advance of said piston and means ior increasing the quantity of duid in advance thereof made effective on travel of said piston beyond the end or said predetermined path.

l5. In combination, a motor comprising a cylinder with a piston normally reciprocable therein in a predetermined path, said cylinder vented` to provide for lfree air displacement in advance of the piston and preclude substantial fluid resistance upon said piston during normal working strokes of the latter and means for checking piston movement should said path be exceeded including means for increasing the fluid resistance to piston movement including means for precluding free displacement of fluid in advance of said piston, and means for increasing the quantity of fluid in advance thereof including means for conducting fluid from behind said piston to the space in advance thereof after the end of said predetermined path is reached.

16. In a motor, in combination, a cylinder, a piston reciprocable therein, and Valve mechanism for said motor including a valve controlling both the admission and exhaust functions for said motor and having controlling means having a pressure area acting to move said valve to exhaust establishing position, and means for supplying pressure to said area and venting pressure therefrom respectively having communication with the cylinder bore at points widely spaced longitudinally of the latter, and having separate communications with said area each having a check valve associated therewith.

17. In a motor, in combination, a cylinder, a single-acting piston reciprocable therein, and valve mechanism forsaid motor including a valve controlling both the admission and exhaust functions for said motor and having a pressure area constantly subject to a pressure in excess .of atmospheric and less than line pressure whereby said valve is biased constantly in one direction, and controlling means for said valve having a pressure area acting to move said valve in the opposite direction, and means for supplying pressure to said area to initiate such movement and vent pressure therefrom to permit reverse movement respectively having check-valve-controlled communication with the cylinder bore at points widely spaced longitudinally of the latter, the first at a point near the end of the working stroke of the piston and the second at a point near the opposite end of the cylinder,

18. In a motor, in combination, a cylinder, a single-acting piston therein, and valve mechanism for said motorvincluding avalve controlling both the admission and exhaust functions of the motor and having means for effecting movement thereof in one direction upon reduction in an opposing force, and means for providing such a force to effect the opposite valve movement including a pressure-fluid-actuated element and means associated therewith including a connection for transmitting pressure thereto after an initial movement of said element and ineffective until movement is started, and means for transmitting only a starting movement to said element ineffective as soon as substantial movement takes place,

19. In a motor, in combination, a cylinder, a piston reciprocable therein, means for continuously venting one end of said cylinder, and means for controlling admission and exhaust with respect to the opposite end of said cylinder including but a single distributing valve element, said valve element moved by motor back pressure to establish admission and having a reverse-movementeiecting pressure device having a plurality of piston-controlled connections with the cylinder bore and providing starting and throwing pressures, said starting pressure connection last uncovered by the piston on the working stroke of the latter. 20. In a motor, in combination, a cylinder, a piston reciprocable therein, means for continuously venting one end of said cylinder, and means for controlling admission and exhaust with respect to the opposite end of said cylinder including but a single distributing valve element, vsaid valve element moved by motor back pressure to establish admission and having a reverse-movement-effecting pressure device having a plurality of piston-controlled check-valved connections with the'v cylinder bore and providing starting and throwing pressures, said starting pressure connection last uncovered by the piston on the working stroke of the latter.

21, In a motor, in combination, a cylinder, a single-acting piston reciprocable therein, and valve mechanism for saidy motor including a valve controlling both the admission and exhaust functions of said motor and controlling means for said valve having a pressure area acting to move said valve in one direction, and means for supplying pressure to said area and venting pressure therefrom respectively having check-valve-controlled communications withthe cylinder bore at points widely spaced longitudinally of the latter, the first at a point uncovered bythe piston nearthe end of the working stroke of the latter and the second at a point near the opposite end of the cylinder.

22. In a motor, in combination, a cylinder, a single-acting piston reciprocableV therein, and valve mechanism for said motor including a valve controlling both'the admission and exhaust functions of said motor and controlling means for said valve having a pressure area acting to move said valve in a direction to interrupt admission and establish exhaust, and means for supplying pressure to said area and venting pressure therefrom respectively having check-valve-controlled communications with the cylinder bore at points widely spaced longitudinally of the latter, the first at a point uncovered by the piston near the end. of the working stroke o-f the latter. and the second at a point near the opposite end-of the cylinder.

23. In a motor, in combination, av cylinder, a single-acting piston reciprocable therein, and valve mechanism for said motor including a valve controlling both the admission and exhaust functions of said motor and controlling means for said valve having a pressure area acting to move said valve in a direction to interrupt admission and establish exhaust, and means for supplying pressure to said area and venting pressure therefrom respectively having check-valve-controlled communications with the cylinder borey at points widely spaced longitudinally of the latter, the rst at a point uncovered by the piston near the end of the working' stroke of the latter and the second at a point near the opposite end of the cylinder, said valve having means for moving the same in the opposite direction including a second pressure area and means for subjecting the same constantly to a pressureI intermediate supply pressure and atmospheric pressure.

24. Ina motor, in combination, a cylinder, a piston reciprocable therein, means for continuously venting one end of said cylinder, and means for controlling admission and exhaust with respect to the opposite end of the cylinder including a valve performing both admission and exhaust functions and having associated throwing means including means for continuously exerting in one direction a pressure on said valve adequate to throw the same in said direction when uno-pposed, and means for exerting on said valve throughout nearly the entire piston travel in one direction a superior pressure acting in opposition to and overcoming said first mentioned pressure,

and for maintaining said valve, throughout nearlyr vill for controlling admission and exhaust with respect to the opposite end of said cylinder including a valve operative in opposite positions tc effect the admission and exhaust functions, means for moving said valve in one direction by a pressure less than cylinder working pressure, and means for moving said valve in the opposite direction by a higher pressure, said last mentioned means having associated therewith means for trapping the throwing pressure during the major portion of piston movement in one direction` 26. In a motor, in combination, a cylinder, a single acting piston therein, and valve mechanism for said motor including a valve controlling both the admission and exhaust functions of the motor and having means for effecting movement thereof in one direction on reduction in an opposing force, and means for providing such a force to effect the opposite valve movement including a surface subjectable to fluid pressure, means associated with said surface including a valve-controllable connection for transmitting pressure thereto after an initial movement of said surface but ineffective until such movement takes place, and valvecontrollable means for transmitting only a starting movement to said surface ineffective as soon as susbtantial movement takes place.

27. In combination, a motor comprising a cylinder with a piston normally reciprocable therein in a predetermined path, means for controlling distribution of pressure fluid with respect to one end of said cylinder, a vent for providing for free air displacement in advance of the piston during normal working strokes of the latter and overrun by said piston on the latters exceeding its normal path of movement by a predetermined amount, and means' for preventing free venting of said cylinder should said piston exceed its normal stroke, said last mentioned means including means operative on a predetermined increase in cylinder pressure adjacent said vent to partially close said vent.

28. In combination, a motor comprising a cylinder with a piston normally reciprocable therein in a predetermined path, and means for checking piston movement should said path be exceeded including means for conducting fluid from behind said piston to the space in advance thereof, a vent for providing for free air displacement in advance of said piston during normal working strokes of the latter and overrun by said piston when the normal working stroke of said piston is exceeded by a predetermined amount, andA means associated with said vent for preventing free venting of said cylinder including means operative on a predetermined increase of cylinder pressure adjacent said vent to partially close said vent.

29. In combination, a motor comprising a cylinder with a piston normally reciprocable therein in a predetermined path, means for admitting and exhausting motive fluid with respect to one end of the cylinder, and means for connecting said cylinder to atmosphere and overrun by said piston when the normal stroke of the piston is exceeded by a predetermined amount, said last mentioned means including a valve governed by pressure differentials between atmosphere and said cylinder and providing different areas of communication with the atmosphere automatically in accordance with said pressure differentials.

30. In combination, a motor comprising a cylinder with a piston normally reciprocable therein in a predetermined path, means for admitting and exhausting motive fluid with respect to one end of the cylinder, and means for connecting said cylinder to atmosphere which means is overrun by said piston when the normal stroke of the piston is exceeded by a predetermined amount, said last mentioned means including valved and unvalved passages and providing diierent areas of communication automatically in dependence upon pressure differentials between atmosphere and said cylinder, the larger area adequate to preclude material resistance to fluid pressure on the non-working side of the piston during normal working strokes of the latter.

31. In combination, a single-acting expansiblechamber motor including a reciprocable piston and a cylinder, the latter materially elongated beyond the normal range of piston movement, said cylinder having associated with the inactive end thereof cushion means for controlling piston speed, said cushion means including in communication with said cylinder at a point beyond the normal stroke limit of the motor piston but overrun by the piston upon abnormal strokes, means for providing a continuous limited venting of the inactive end of said motor, and means for providing a larger communication between said inactive end and the atmosphera said last mentioned means having a controlling valve maintained in a position to preclude at normal piston speeds the oiering of material resistance to motor piston movement but movable, upon a higher rate of piston movement in a working direction, in a closing direction.

WADE I-I. WINEMAN. 

